High-voltage arrester



June 30, 1953 I SANDS 2,644,115

HIGH-VOLTAGE ARRESTER Filed Jan. 26, 1951 ""4 I N V EN TOR.

ROY s. smos ATTORNE Y Patented June 30, 1953 HIGH-VOLTAGE ARRESTER RoyG. Sands, Waukegan, Ill., assignor to Automatic Electric Laboratories,Inc., Chicago, 111., a corporation of Delaware Application January 26,1951, Serial No. 208,011

4 Claims.

The present invention relates in general to protective devices forelectrical circuits and more particularly to arrester's which arecapable of protecting communication circuits from destructive damagewhen crossed with extremely high voltage lines.

Communication circuits are, at the present, normally protected at boththe central office and substations from abnormal currents, such as wouldbe found when the circuit is struck by lightning or is crossed with ahigh power transmission line. These protectors have taken many forms andgenerally consist of an automatic high voltage discharge block, or afuse, or a combination thereof. Such arrangements have been generallyaccepted throughout the communication industry and are recognized asbeing both valuable and necessary in order to protect both property andlife from the hazards of high potential currents.

The recent expansion of the Rural Electrification Administration haspresented the communication field with a new and alarming hazard. Thehigh voltages and currents carried by the REA lines far surpass thosecarried by high power lines in the past. The basic fear created by theselines is due to the fact that the voltages and currents carried by themgreatly exceed the conditions under which the present day protectivedevices were designed to operate satisfactorily. In fact, the powercarried by these lines is sufficient to break down the insulation provided by the standard protective devices and is capable of exposing thecommunication equipment to the dangers of a high potential in spite oftheir use.

It is therefore an object of this invention to provide a novelprotective device which is capable of protecting circuits from injurydue to the extremely high voltages. A further object of the invention isto provide an overvoltage protecting device which is rapid in operation,is capable of automatically freeing the circuit after the hazard hasbeen removed and iscapable of operating many times before it requireshuman attention. A further object of the invention is to provide anefiicient and reliable device for protecting several of such circuitsfrom injury due to high voltages which is economical to manufacture.

Other objects will be clear from the following specification taken inconnection with the annexed drawings in which:

Figure 1 is a front view in which the cover has been broken away to showthe components of the structure;

Figure 2 is a sectional view taken along line 2--2 of Figure 1;

Figure 3 is a perspective View of the bi-metallic element, which will bemore specifically described hereinafter;

Figure 4 is a sectional view taken along line 4-4 of Figure l. i

As shown in Figures 1 and 4, the protector includes a base it whichsupports an insulating block H, made of a suitable electrical insulatingmaterial, such as glazed porcelain. The base [0 and the block H aresupported by a bracket l2 and are fastened thereto by any well knownmeans, such as machine screws 13. The bracket i2 may be constructed inany manner suitable to the location and position in which the protectoris to be mounted. The entire structure may be covered and protected by acover M which can be loci-red. place or secured to the base Ill by anyof the well known locking means, such as screw i5.

The block of insulating material II has a series of raised embossings 20and 2|. They include one centrally located embossing 20 and four outerembossings 2!, which are disposed about the central embossing 2D. Thisarrangement is only one of those which could be used within the spiritof the invention, the particular number of outer embossings notnecessarily being fixed at four. A heavy carbon electrode 22 is mountedon the central embossing 20 and a similar heavy carbon electrode 23 ismounted on each of the outer embossings 2 l. The outer electrodes 23 areeach secured in place by a fastener 24 which engages a conductorterminal clip 25. Each of these clips 25 is electrically connected to aheavy current conductor 26, by which the electrode may be connected toany desired line conductor or other portion of a communication circuit,not shown. The space between the adjacent sides of the central electrode22 and each of the outer electrodes 23 is carefully adjusted, as willhereinafter be shown necessary. These spaces are all approximately equaland are somewhat smaller than the spaces between adjoining outerelectrodes 23.

The center electrode 22 is held in position by shaft 21, the bottom endof which engages a conductor terminal clip 28 and the upper end of whichis engaged by a washer 29 and lock-nut 30. The conductor terminal clipis electrically connected to a heavy current conductor 28a, the otherend of which (not shown) is connected to ground. A tubular spacingbushing 3| may be mounted on the upper end of the shaft 21 in order tosupport a bi-metallic element 32. The

bi-metallic element 32, as shown in figure 3, has four projections 33extending outward from the hole which engages shaft 21. Each of thesepro jections is arranged to lie directly above one of the outerelectrodes 23. The bi-metallic ele ment 32 may be fastened to the shaft21 by any suitable means, such as the lock-nut 34 and washer 35.

A heavy carbon contact block 36 is attached to the end of each of thebi-metallic element projections 33 and is fixed thereto by fasteners 31.The lower face 38 of each of the contact blocks 36 is diagonally biasedso that the contact block 36 will abut its adjacent outer electrode 23in surface contact when the bi-metallic element projection 33 is flexeddownward, as will be hereinafter explained. The space between thecontact block 36 and its adjacent electrode 23, at the nearest point, isadjusted so that it is equal to the space between the outer electrode 23and the central electrode 22.

Now that the structural features of my new protector have been set outin detail, I will explain its operation when an extremely high voltagecurrent is attached to the circuit to which one of the conductors 26 isconnected. This con nection will carry the potential to the outerelectrode 23 which is associated with the circuit so effected. If thisforeign potential approaches the voltage and current limits of thestandard communication circuit protectors, it will be sufiicient tobreak down the air gap between the outer electrode 23 and the centralelectrode 22 to form a primary spark gap between said electrodes. Sincethe contact 36 is also connected to ground through element 32 and shaft21, a secondary spark gap will be formed between the contact 33 and theouter electrode 23. The heat formed by these two spark gaps is veryintense and immediately causes the bi-metallic element projection 33,which is associated with the spark gap contact 36, to flex downward andbring the contact 38 and outer electrode 23 into contact. Since thecontact 33 has its lower face 38 biased, the contact 36 and electrode 23are brought into surface to surface contact, which will short circuitand completely disable the spark gaps. The bi-metallic element 32 willremain flexed and maintain its projection 33 in a downward position aslong as the high voltage current is fiOWlllg therethrough.

After the source of high voltage current has been disconnected from thecommunication circuit and its resulting potential removed from electrode23, the bi-metallic element 32 will be free from the effects of both thespark gap heat and the conduction of high voltage current and will, as aresult, restore its projection 33 to its normal inoperative position asshown in Figure 1. The protector is now in condition for reoperationshould the source of high potential again be connected to the associatedcommunication circuit.

Thus it can now be seen that each outer electrode 23, its adjoiningcarbon contact 36 and associated bi-metallic element projection 33 forma separate arrester unit in conjunction with the common centralelectrode 22. Normally, each of these units is available for protectinga different circuit, the particular arrangement disclosed herein beingcapable of protecting four such circuits. The number of circuits to beprotected and, correspondingly, the number and arrangement of outerelectrodes 23 could be varied in accordance with the conditions in whichthe protector is to be used without avoiding the scope of the invention.If, in the future, any communication circuit is exposed to the hazard ofa high power line which exceeds the rated capacity of one of thesearrester units, two or more of the units may be connected to the circuitin parallel by merely connecting two or more of the outer electrodes 23to the circuit instead of one. This will then reduce the powerdischarged by each unit to a value well within its capacity.

A protector made in accordance with my invention will successfully andsatisfactorily arrest high voltage currents of the order of 12 kilovoltsand will successfully and satisfactorily reoperate after the arresterhas automatically reset itself. These currents are arrested in anextremely short period of time after they are imposed upon the line, thetime lapse in some cases being of the order of 5 milliseconds. Fromthis, it may readily be seen that this protector will not only groundthe foreign high potential, but will operate rapidly enough to preventany destruction to equipment or persons during the time such potentialsare imposed upon the line. This protector is not intended to replace theprotective equipment now in use in communication equipment but isintended to supplement such devices and arrest foreign currents whichexceed the capacity of the standard devices.

Having described my invention in detail what I desire to protect byLetters Patent in the United States is:

1. In a high voltage current protector, three carbon elements, the firstand second. of said elements immovably mounted adjacent one another, theside surfaces of the first and second of said elements forming a firstspark gap, a bi-metallic strip, one end of said bi-metallic stripmounted on said first element, the other end of said lei-metallic stripsupporting said third element so that the surfaces of said. second andthird elements form a second spark gap, said first element, saidbimetallic strip, and said third element forming a current path, saidsecond element passing high voltage current to said first and thirdelements through said spark gaps, said bi metallic strip flexedresponsive to the heat of said spark gaps to bring said third elementinto contact with said second element to form a high current dischargepath from said second element directly to the third of said elements andthrough said bimetallic strip and said first element.

2. In a high. voltage current protector, a centrally disposed firstelectrode immovably mounted in said protector, a plurality of secondelectrodes immovably mounted in said protector and disposed about saidfirst electrode in spaced apart relation and each of said secondelectrodes having a surface in close proximity with a side of said firstelectrode to form a plurality of first spark gaps, a bi-metallic elementmounted on said first electrode and means including said element forforming a plurality of second spark gaps with each of said secondelectrodes, said element and means forming a current path from each ofsaid second spark gaps to said first electrode, said element flexedresponsive to the heat of a high Voltage spark at any of said pluralityof second spark gaps to close that spark gap to form a high currentdischarge path from said second electrode directly to said means and tosaid first electrode.

3. In a high voltage current protector, a centrally disposed firstelectrode, a plurality of sec-- ond electrodes disposed about said firstelectrode in spaced apart relation and each of said second electrodeshaving a surface in close proximity with a side of said first electrodeto form a plurality of first high voltage discharge gaps from saidplurality of second electrodes to said first electrode, a bi-metallicelement mounted on said first electrode and having a plurality ofprojections, a plurality of third electrodes, one of said thirdelectrodes mounted on each of said projections, each third electrode inclose proximity with respective ones of said second electrodes to form aplurality of second high voltage discharge gaps, each projection of saidbi-metallic element flexing responsive to the heat generated by itscorresponding second high voltage gap to move said corresponding thirdelectrode into contact with said associated second electrode wherebysaid last mentioned high voltage discharge gap is closed.

4. In a protector as claimed in claim 3, each of said third electrodeshaving a surface, which in close proximity to said associated secondelectrode, angularly disposed so that the flexing of each of saidprojections brings the planes of the angularly disposed surfaces of saidelectrodes in to parallel contact with the respective planes of saidsecond electrodes.

ROY G. SANDS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 768,196 Rolfe Aug. 23, 1904 2,124,364 Brach July 19, 19382,141,490 Sands Dec. 2'7, 1938

